Content addressable memory (CAM) is a type of memory that can perform a search operation in which a data string may be input as search content and the resulting output is an address of a location in the memory that stores matching data (if there is any). This is in contrast to a read operation in which an address is input and the resulting output is the data stored in the memory location corresponding to the searched address. Certain CAMs may be able to perform both the aforementioned search operation and the aforementioned read operation, while non-CAM memories may be able to perform the read operation but not the search operation.
Ternary content addressable memory (TCAM) is a type of CAM in which the bit cells can store a wildcard data value in addition to two binary data values. When a bit cell that stores the wildcard value is searched, the result is a match regardless of what search criterion is used to search the bit cell. Certain TCAMs may also allow a search to be conducted on the basis of a wildcard search criterion. When a bit cell is searched based on the wildcard search criterion, the result is a match regardless of what value is stored in the bit cell.